Performance and API improvements when working with lists of installed themes

Support for installing child themes from the WordPress Themes Directory

Remember, if you find something you think is a bug, report it! You can bring it up in the alpha/beta forum, you can email it to the wp-testers list, or if you’ve confirmed that other people are experiencing the same bug, you can report it on the WordPress Core Trac. (We recommend starting in the forum or on the mailing list.)